Sometimes you do want to push some custom attribute (e.g. ad_source) to a new chat user so the data will be viable to you inside Exceed, so you use this custom attribute to tailor your follow-up emails to the contact, or just to push this new attribute to the CRM.
In order to add this custom attribute all you have to do is to add this line of code:
for every custom attribute you'd like to push to a chat user.
Note that the data will be reflected inside Exceed just after the chat user engaged with the chat.